Seeing Coldest Blobs in the Universe in New Light

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Physicists have come up with a new way to gaze longingly at some
of the weirdest matter on Earth — the super-cold, super-calm gas
called a Bose-Einstein condensate.

While scientists have been able to steal quick glimpses of the
unusual gas, until now, simply snapping a picture of a
Bose-Einstein condensate (BEC) often destroyed it by adding
extra energy from light.

By creating a new computer model, detailed today (Nov. 28) in the
New Journal of Physics, the researchers have figured out a way to
re-route this heat and keep BECs chilled even during long imaging
sessions.

In principle, Hush said, the proposal "could allow a BEC to be
imaged indefinitely, during which we will be able to directly
look at the BEC and even control it using feedback."

"Being able to play around with a
quantum object close to absolute zero right then and there is
really exciting," he added.

Bose-Einstein condensates are atoms or other particles, such as
photons, chilled to nearly absolute zero. The atoms are so
languid they behave strangely, as a single, bloblike mass. The
slow-moving nature of the particles means scientists can easily
track and study atomic processes, such as
atomic spins, by studying Bose-Einstein condensates. (They
are named after Albert Einstein and the Indian theorist Satyendra
Nath Bose.)

For more than a decade, physicists have peered at BECs with
off-resonant photons, a type of laser imaging that tends scatter
its energy off the
super-chilled atoms instead of adding heat. But even this
method will work for only a few tries, eventually destroying the
condensate after a handful of images, Hush said.

To improve the imaging technique, Hush and his colleagues built a
sophisticated computer model that simulates both off-resonant
light and the weird behavior of Bose-Einstein condensates. The
model revealed a never-before-seen heating effect caused by
off-resonant imaging.

"The particular discovery presented in this paper was actually
first thought to be a bug in our code," Hush said. "We thought
this because simpler descriptions of BECs did not predict this
heating."

Via their model, the researchers have devised a filter that
removes the heating effect and feeds the extra energy back into
the magnetic coils used to trap and chill the condensate, which
will help keep the atoms cooled for longer periods. Now, when
inquisitive viewers want to watch the atoms sit around, such
picture-snapping would send more energy into the chill-inducing
coils, actually making the condensate even colder.

The next step is trying out the filter in a real-world
experiment.

"Once we had isolated what was causing the heating it was easy to
come up with the feedback to correct it," Hush said. "Results
like this are very promising, and make me hopeful that an
experimental demonstration of feedback with a BEC may be possible
in the near future."